Because of their outstanding properties, synthetic polymers are used in a wide variety of applications. They are used, for example, as fibers, films, coatings and shaped objects. In almost all of these applications, as well as in the processing of the polymers, a high degree of thermal stability is required. Many polymers are not, themselves, sufficiently stable at elevated temperatures as to resist deterioration with the result that they develop color, lose strength, etc. These polymers can be fortified against such deterioration by the addition of small proportions of certain types of compounds.
Polymers which are susceptible to deterioration at elevated temperatures and which are benefited with respect to reduced deterioration by the presence of the phosphitic-isocyanurates herein include styrene polymers such as polystyrene, high-impact polystyrene, SBR, ABS resins and MBS resins, polyamides, polycarbonates, olefin polymers such as polypropylene, low density polyethylene, high density polyethylene, polyisoprene, EPDM polymers, and copolymers of ethylene; polyvinyl chloride, polyvinyl acetate, polyvinyl ethers, polyvinyl-acetals, polyesters, polyurethanes, and polyacrylonitrile.
Japanese Patent Publication No. 79/30241 deals with this problem. It shows polyethylene and polypropylene compositions containing 2,2',2"-(1,3,5-s-triazine-2,4,6- 1H,3H,5H, -trionyltris ethylene bis-(alkylphenyl)phosphites.
The stabilization of synthetic resins in general by the presence of a small proportion of bis-(2,4-ditertiarybutylphenyl)pentaerythritol diphosphite or bis-(2-tertiarybutyl-5-methylphenyl)pentaerythritol disphosphite is shown in published Japanese application No. 79/25,951. Polyethylene stabilized compositions also contain calcium stearate, pentaerythritol tetrakis-(3,5-ditertiarybutyl-4-hydrox-phenyl propionate) and dilauryl thiodipropionate.
U.K. Pat. No. 1,526,603 shows the use of bis-(alkylphenyl)pentaerythritol diphosphites as stabilizers for polypropylene. The bis-(2,4-ditertiarybutylphenyl)pentaerythritol diphosphite is shown specifically, in combination with calcium stearate and tetrakis-methylene-3(3',5'-ditertiarybutyl-4'-hydroxyphenyl)propionate methane.